This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This project was initiated to design and implement in vivo experiments to analyze immune responses in vivo in mice, within a systematically integrated process that cycles from experimental design, to data collection, to data analysis, to parameter estimation, to goodness of fit determination, to deduction from model, and back to experimental design. In the current reporting period, significant progress has been made, which suggested the following. We discovered that distinct subsets of DCs sequentially migrate to the draining LNs after immunization with OVA+LPS. The caveat to this is that the change in DC numbers observed may instead reflect differences in differentiation, proliferation or apoptosis. Experiments to clarify these issues are in progress, as follows: 1) That IL-12 production is mediated predominantly by Lymphoid DCs and Langerhans DC, but by myeloid DCs or dermal DCs, suggesting a division of labor amongst the DC subsets. 2) That antigen-presentation is mediated by all DC subsets.